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June 19, 1923. 1,459,070

A. P. MORGAN RHEOSTAT FledLJunB 28. 1921 .9 Jg 21 J9 I5 Patented June 19, 1923.

UNITED STATES ALFRED P. MORGAN, OF MONTCLAIR, NEW JERSEY.

RHEOSTAT.

Application led Iune-28, 1921,

To all whom it may concern.'

Beit known that I, ALFRED P. MORGAN, a citizen of the United States, residing in the town of Montclair, county of Essex, and

State of New Jersey, have invented certain new and useful Improvements in Rheostats, of which the following is a full, clear, and exact description, reference being had to the accompanying drawings, forming a part of this specification.

The object of my invention is to provide a rheostat adapted for mounting either upon the face or back of a panel as may be necessary or desired, and operable manually at the face of the panel. More particular objects are the provision in such a rheostat of a rotatable shaft carrying the swinging contact element and having a knob to facilitate the rotation of said shaft manually, which shaft and associated elements shall be reversible with respect to the variable resistance element and its mounting; and further, the provision in such a rheostat of an electrical connection between the said shaft and the variable resistance element such that by a simple shifting of such connection, the resistance may either be increased or decreased by rotation of the contact in one direction, and conversely may either be increased or decreased by rotation in the opposite direction, as desired. Features of particular advantage and utility sought, are the simplified and compact construction of the resistance element and its mountings, affording economy of manufacture and assembly.

With these objects in View, my invention consists, generally considered, in a rheostat having the resistance element Wound upon a circular insulating core of a cross-section corresponding to an interrupted groove of rectangular cross-section formed in the insulating base and into which the resistance element is adapted to be fitted as an entity; a Contact arm adapted to sweep over the face of such resistance element and mounted resistance element is mounted, the complete article being formed for mounting upon the front of a board either horizontally or vertically disposed, as illustrated in Figure 5. Particularly considered, my invention consists in a rheostat as just described, Whose Serial No. 480,963.

rotatable shaft is adapted to be withdrawn f rom that face of the base carrying the resistance element and to be reinserted therein from the side opposite thereto after the base has been mounted on the back of a Apanel or the like board lying either in a horizontal or vertical position, as illustrated in Figure l. Such adaptability renders this rheostat reversible as to its mounting, a capability particularly desired in rheostats intended for mounting upon a vacuum tube panel for radio communication to vary the current in the lamp filament of the valve, and thereby control the temperature of the filament. S'uch panels are preferably of limited dimensions, and necessarily mount a considerable number of pieces of apparatus, and one ob- Ject sought by builders of this class of radio apparatus has been to economize space thereon that all adjustments requiring manual manipulation may be within the easy reach of the o erator, and upon the front of the panel. y my invention, the rheostat, of which several may be required on the same panel, can be disposed, if necessary, upon the back of the panel, with only its knob upon the panel face, and space thus economized.

The invention is clearly illustrated in the accompanying drawings, in which like numerals indicate the like parts throughout the several figures, and in which Figure l is a view in sectional elevation upon the lines 1-1 of Figure 2, looking in the direction indicated by the arrow, of a rheostat mounted upon a panel, shown horizontally as broken off at its ends, the panel being intermediate the manually operable knob on the `shaft and the resistance element. Figure 2 is a plan View of the rheostat mounted as in Figure l, viewed from below. Figure 3 is a top view in plan of the rheost'at mounted as in Figure 1. Figure 4 is a top plan View of a rheostat mounted wholly upon the face of a panel, and Fig-- ure 5 is a perspective view ot the rheostat mounted as in Figure 4, the panel being in dicated in section, the shaft, securing screw and contour of the inner face of the base being indicated in dotted lines.

Like numerals of reference indicate the same or corresponding parts throughout these several figures, in which l desi nates a panel; 2 the rheostat base of insu ating material; 3 the screws attaching the base to the panel; 4 the reversible shaft and 5 the milled knob thereon, and 6 the screw attaehingthis knobto the shaft. 7 is an interrupted circular groove of rectangular cross-section in the base. 8 is the insulating core Whose contour corresponds to said groove. 9 is the windin of Wire on said core, and constituting tlie resistance ele.- ment. 10 and 11 are binding posts mounted on said base adjacent. the-ends of the core. 1 2 is a'contact arm attached to said shaft, rotatable therewith and adapted to sweep over the windings of the resistance element. 13 and 14 are adjustable collars pinned'to the shaft and adapted to rotate therewith and to secure the base thereto. 15 and j16 are plates mounted beneath the binding posts 10 and 11 and held to 4the base by the-screws 17 and 18, and carrying stops 19 and 20. 21 is a conductin Spanner of spring metal clamped at one en by the plate 15 and at the other end formed as a split washer about the shaft. 22 is a spacing washer.V 23 is a pointer which is preferably employed to indicate the position of the contact arm relatively to the resistance .upon a scale 24 which is preferably laid` out on the panel .when the rheostat is back-mounted. In lieu of such pointer, an indicator 25 may be engraved upon the knob in register with the contact arm. The extremity ofithis arm ispreferabl convex on its under side .to minimize friction on the resistance coil and to improve contact therewith. The electrical connection shown is from binding post 11, plate 15, spanner 21, shaft 4, contact arm 12, coil 9, whose end, not shown, is clamped below the head of screw 1S, through this screw to plate 16 and binding post 10. By4 attaching the Spanner to the.plate 16 instead of to plate 17, as shown, and detaching the end of the coil 9 from the screw 18, and attaching the other end of the coil to the screw 17, the order of. cutting in or cutting out the resistance may be reversed. The order of cutting in or cutting out the resistance will preferably be by rotation of the shaft in uniform direction. As shown, when front-mounted, counter-clock-wise rotation of the knob cuts out resistance. In order that like direction of rotation may produce like results when the rheostat is back-mounted, a reversal of resistance-connections is necessary. This may be efected as described, or the resistance element itself may be removed, reversed and reinserted in the` base. As this element is removably mounted in the base, this operation is simplified. In the figures, one end of the resistance wire only is continued beyond the core as a lead to screv7 18. This end is detached therefrom, the element removed, reversed and reinserted, thereby bringing the free lead into proximity to seien" 1T beneath Whose head it is clamped, the Spanner 21 being transposed from screw 17 to screw 18, associated with plate 16 and binding post 12. When dcsired, the resistance element may be removed as described and replaced by :in ele- -Inent of other resistance value.

A particular feature of manufacturing economy is the one-piece recessed base of' insulating material, such as condensite, adapted tobemolded with the interrupted rec.- tangular groove therein in which tbe correspondingly shaped resistance element is rcceivedwith a forced fit and firmly held Without need for supplemental securingr means. The spacing washer 22 and the screw 6 afford a tolerance adapted to permit adjustment to the slightly varying thicknesses of panel boards. The completed article thus affords a self-contained rheostat capable of reversibility as to mounting without the substitution or addition of extraneous parts, and capable of reversibility as to direction of variation of its resistance.

Having thus described the preferred physical embodiment of my invention` which, it will be understood by those skilled in the art, is susceptible ot modification without departure from the spirit of this disclosure, I claim:

1. In a rheostat, a circularly grooved base of insulating material, a core ot insulating material having a configuration corresponding to said groove, and a. variable resistance conductor spirally disposed about said core, said core and conductor being adapted to fit removably within said groove and to project therefrom above the face of said base. and being further adapted' to be removed. reversed and reinserted in said groove when it is desired to change the order ot resistance-variation.

2. In a rheostat. a circularly ,ffrooved base of insulating material, a core of insulating;f material having a configuration corresponding to said groove. a variable resistance comprising a conductor spirallyy disposed about said core, said core and conductor bein;r adapted to it removably within said groove and to project therefrom above the face of said base, and being adapted to be removed` vreversed and reinserted 1n said groove, a

shaft of conducting material rotatably mounted in said base, and a contact arm carried by said shaft and adapted to sweep over the projecting coils of said resistance, said Contact arm having a convex face adapted to engage said coils.

3. In a rheostat, a circularly grooved base of insulating material` a core of insulatingY material having a configuration corresponding to said groove, a resistance conductor spil-ally disposed about said core` said core and conductor being:r adapted to fit removably within said groove and to project therefrom above the face of said base,- a pair of terminals mounted on said base, an electrical lili connection between said conductor and one of said terminals, a shaft of conducting material rotatably mounted in said base, an electrical connection between said shaft and the other terminal consisting of a spring washer surrounding said shaft and having an extension joined to a plate connected to said other terminal, an adjustable collar upon said shaft adapted to bear against said washer and to rotate with said shaft,'and a contact arm carried by said shaft and adapted to sweep over the projecting coils of said resistance.

4. -In a rheostat, a circularly gTooved base -of insulating material. a core of insulating material having a configuration corresponding to said groove, a resistance conductor spirally disposed about said core, said core and conductor being adapted to fit removably within said groove and to project therefrom above the face of said base, a shaft of conducting material rotatably mounted in said base, means adapted to adjust the position of said shaft relatively to said base, line terminals mounted on said base, an electrical connection between said shaft and one of said terminals, the said connector consistin of a split washer surrounding said shaft an having an extension adapted to be electrically connected t0 said terminal, an,adjust able collar upon said shaft adapted to position said shaft and to bear against said washer and to rotate with said shaft, a second adjustable collar on said shaft and on the 'opposite face of said base from the split washer, a contact arm carried by said shaft and adapted to sweep over the projecting coils of said resistance, a plate beneath each line terminal, and stops upon said plates adapted to limit the travel of said contact arm in either direction.

5. In a rheostat, an insulating base, a variable resistance thereon, a rotatable shaft mounted-in said base, a knob on said shaft for manual manipulation thereof and vertically disposed relatively to said base, a contact arm on said shaft adapted to be adjustably positioned relatively to said shaft, and means aldapted to permit said knob to occupy a plurality of operable positions relatively to the shaft and tothe base.

6. In a rheostat, an insulating base, a variable resistance comprising an entity separably mounted in said base, a rotatable shaft vertically disposed and extending through said base, and adapted at one end to manual manipulation, `and a contact arm on said shaft adapted to engage said resistance, the said base being reversible relatively to said shaft.

7. In a rheostat, a circular, insulating base, a shaft concentrically mounted therein, a resistance element removably mounted in a curved slot in the face of said base and concentric with said shaft, a milled knol removably attached to an end of said shaft, and means adapted to permit the reversal of said shaft relatively to said base.

8. In a rheostat, an insulating base, a shaft adjustably mounted therethrough, a variable resistance element mounted in one face of said base, a travelling contact carried by said shaft, means adapted to rotate said shaft, and adjustable means including said shaft adapted to mount said base on a panel in a plurality of positions.

9. In a rheostat, a reversible insulating base, a shaft vertically mounted relatively to said base, a knob on said shaft, means adapted to vary the distance of said knob from said base, and means adapted to position said shaft relatively to the base.

10. In a rheostat, a reversible base, a variable resistance and line terminals mounted upon said base, a shaft centrally disposed relatively to said resistance, means adapted to permit manual rotation of said shaft, means adapted to position said shaft relatively to said base, and reversible contact elements between said resistance and the line terminals adapted to permit the like direction of rotation of said shaft to ei'ect like variations of the resistance.

ALFRED P. MORGAN. 

